1. An electroencephalogram (study of electrical current within the brain) indicating the absence of electric potentials of cerebral origin, indicative under certain specified conditions of cerebral death.
2. An electroencephalogram or the graphic recording of the electric discharges of the cerebral cortex as detected by electrodes on the surface of the scalp in which no recognizable waveforms or deviations from the baseline of electrical activity can be discerned as arising from the brain.
3. A graphic chart on which no tracings are recorded during electroencephalography, indicating a lack of brain wave activity.

Flat readings are indicative of brain death except in cases of profound hypothermia and central nervous system depression.